1. Field of the Invention
The present invention generally relates to acoustic imaging and, more specifically, to ultrasonic imaging systems and methods that utilize acoustically non-focusing lenses.
2. Description of the Related Art
Conventional one-dimensional (1-D) phased array transducers utilized for ultrasonic imaging typically incorporate lenses that focus acoustic beams transmitted from the transducers. In particular, the material properties of such a lens typically are selected to focus an acoustic beam from a transducer in an elevational dimension. The elevational dimension also may be focused mechanically, such as by implementing a concave shape at the array of the transducer. The lateral dimension typically is focused electronically.
By way of example, a conventional 1-D phased array transducer utilizes a lens that promotes focusing of transmitted acoustic energy within a body, e.g., a human body. Oftentimes, the material of such a lens possesses an acoustic velocity that is less than that of the human body (approximately 1.5 mm/xcexcsec). So provided, the acoustic energy propagated into the body by the lens tends to converge or focus within the body. Focusing of acoustic energy transmitted from a conventional 1-D transducer within a body is depicted schematically in FIG. 1.
In FIG. 1, representative acoustic waves 12, 14, 16, 18, and 20 are shown being transmitted from transducer 22 via focusing lens 24. As depicted therein, the acoustic waves tend to focus as they propagate deeper into body 30 due, at least in part, to the material of the lens.
As is known, acoustic energy propagates at various velocities and with various wave-front shapes depending upon, for example, the acoustic velocity and acoustic impedance of a material(s) through which the acoustic energy is propagated. For instance, the closer the acoustic velocity of a lens material is to that of the body, the closer the energy is transmitted from a transducer and into the body at the incident angle. Additionally, the closer the acoustic impedance is between the lens material and that of the body, the more ultrasonic energy is transmitted from the transducer and into the body.
Since it is known to electronically focus acoustic beams propagated from two-dimensional (2-D) transducers in both the elevational and lateral dimensions, there may no longer be a desire to mechanically focus acoustic beams propagated into a body to the degree typically provided. However, many 2-D transducers continue to utilize convex lenses, which tend to mechanically focus propagated acoustic energy. Therefore, there is a need for improved systems and methods that address these and/or other shortcomings of the prior art.
Briefly described, the present invention generally relates to acoustic imaging. In this regard, embodiments of the invention may be construed as providing acoustic imaging systems. In a preferred embodiment, the system includes a transducer lens configured to mate with a transducer body. The transducer lens is formed, at least partially, of an acoustic-matching material, which exhibits acoustic properties corresponding to acoustic properties of a body to be imaged. So configured, acoustic energy transmitted from the transducer lens and into the body can be substantially non-focusing until modified by electronic focusing techniques.
Other embodiments of the present invention may be construed as providing methods for acoustically imaging a patient, for example. A preferred method comprises the steps of: (1) providing a transducer having a transducer lens formed, at least partially, of an acoustic-matching material; and (2) propagating acoustic waves from the transducer lens.
Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims.